Oxytocin increases after affiliative interactions in male Barbary macaques.

Mammals living in stable social groups often mitigate the costs of group living through the formation of social bonds and cooperative relationships. The neuropeptide hormone oxytocin (OT) is proposed to promote both bonding and cooperation although only a limited number of studies have investigated this under natural conditions. Our aim was to assess the role of OT in bonding and cooperation in male Barbary macaques (Macaca sylvanus). First, we tested for an effect of affiliation - grooming and triadic male-infant-male interactions - with bond and non-bond partners on urinary OT levels. Second, we tested whether grooming interactions (and thus increased OT levels) increase a male's general propensity to cooperate in polyadic conflicts. We collected >4000 h of behavioral data on 14 adult males and measured OT levels from 139 urine samples collected after affiliation and non-social control periods. Urinary OT levels were higher after grooming with any partner. By contrast, OT levels after male-infant-male interactions with any partner or with bond partners were not different from controls but were higher after interactions with non-bond partners. Previous grooming did not increase the likelihood of males to support others in conflicts. Collectively, our results support research indicating that OT is involved in the regulation of adult affiliative relationships. However, our male-infant-male interaction results contradict previous studies suggesting that it is affiliation with bond rather than non-bond partners that trigger the release of OT. Alternatively, OT levels were elevated prior to male-infant-male interactions thus facilitating interaction between non-bond partners. The lack of an association of grooming and subsequent support speaks against an OT linked increase in the general propensity to cooperate.

Thyroid hormone fluctuations indicate a thermoregulatory function in both a tropical (Alouatta palliata) and seasonally cold-habitat (Macaca fuscata) primate.

Thyroid hormones boost animals' basal metabolic rate and represent an important thermoregulatory pathway for mammals that face cold temperatures. Whereas the cold thermal pressures experienced by primates in seasonal habitats at high latitudes and elevations are often apparent, tropical habitats also display distinct wet and dry seasons with modest changes in thermal environment. We assessed seasonal and temperature-related changes in thyroid hormone levels for two primate species in disparate thermal environments, tropical mantled howlers (Alouatta palliata), and seasonally cold-habitat Japanese macaques (Macaca fuscata). We collected urine and feces from animals and used ELISA to quantify levels of the thyroid hormone triiodothyronine (fT3 ). For both species, fT3 levels were significantly higher during the cooler season (wet/winter), consistent with a thermoregulatory role. Likewise, both species displayed greater temperature deficits (i.e., the degree to which animals warm their body temperature relative to ambient) during the cooler season, indicating greater thermoregulatory pressures during this time. Independently of season, Japanese macaques displayed increasing fT3 levels with decreasing recently experienced maximum temperatures, but no relationship between fT3 and recently experienced minimum temperatures. Howlers increased fT3 levels as recently experienced minimum temperatures decreased, although demonstrated the opposite relationship with maximum temperatures. This may reflect natural thermal variation in howlers' habitat: wet seasons had cooler minimum and mean temperatures than the dry season, but similar maximum temperatures. Overall, our findings support the hypothesis that both tropical howlers and seasonally cold-habitat Japanese macaques utilize thyroid hormones as a mechanism to boost metabolism in response to thermoregulatory pressures. This implies that cool thermal pressures faced by tropical primates are sufficient to invoke an energetically costly and relatively longer-term thermoregulatory pathway. The well-established relationship between thyroid hormones and energetics suggests that the seasonal hormonal changes we observed could influence many commonly studied behaviors including food choice, range use, and activity patterns.

Detection of Plasmodium knowlesi DNA in the urine and faeces of a Japanese macaque (Macaca fuscata) over the course of an experimentally induced infection.

BACKGROUND: Diagnostic techniques based on PCR for the detection of Plasmodium DNA can be highly sensitive and specific. The vast majority of these techniques rely, however, on the invasive sampling of blood from infected hosts. There is, currently, considerable interest in the possibility of using body fluids other than blood as sources of parasite DNA for PCR diagnosis. METHODS: Urine and faeces were obtained from a Plasmodium knowlesi infected-Japanese macaque (Macaca fuscata) over the course of an experimentally induced infection. P. knowlesi DNA (PkDNA) extracted from urine and faeces were monitored by nested PCR targeting the P. knowlesi specific cytochrome b (cytb) gene. RESULTS: Urinary PkDNA was detected on day 2, but was not amplified using DNA templates extracted from the samples on day 4, day 5 and day 6. Subsequently, urinary PkDNA was detected from day 7 until day 11, and from day 20 until day 30. PkDNA in faeces was detected from day 7 until day 11, and from day 20 until day 37. Moreover, real-time quantitative PCR showed a remarkable increase in the amount of urinary PkDNA following anti-malarial treatment. This might have been due to the release of a large amount of PkDNA from the degraded parasites as a result of the anti-malarial treatment, leading to excretion of PkDNA in the urine. CONCLUSIONS: The cytb-PCR system using urine and faecal samples is of potential use in molecular epidemiological surveys of malaria. In particular, monkey faecal samples could be useful for the detection of zoonotic primate malaria in its natural hosts.

Urinary C-peptide measurement as a marker of nutritional status in macaques.

Studies of the nutritional status of wild animals are important in a wide range of research areas such as ecology, behavioural ecology and reproductive biology. However, they have so far been strongly limited by the indirect nature of the available non-invasive tools for the measurement of individual energetic status. The measurement of urinary C-peptide (UCP), which in humans and great apes shows a close link to individual nutritional status, may be a more direct, non-invasive tool for such studies in other primates as well and possibly even in non-primate mammals. Here, we test the suitability of UCPs as markers of nutritional status in non-hominid primates, investigating relationships between UCPs and body-mass-index (BMI), skinfold fatness, and plasma C-peptide levels in captive and free-ranging macaques. We also conducted a food reduction experiment, with daily monitoring of body weight and UCP levels. UCP levels showed significant positive correlations with BMI and skinfold fatness in both captive and free-ranging animals and with plasma C-peptide levels in captive ones. In the feeding experiment, UCP levels were positively correlated with changes in body mass and were significantly lower during food reduction than during re-feeding and the pre-experimental control condition. We conclude that UCPs may be used as reliable biomarkers of body condition and nutritional status in studies of free-ranging catarrhines. Our results open exciting opportunities for energetic studies on free-ranging primates and possibly also other mammals.

Urine as another potential source for template DNA in polymerase chain reaction (PCR).

This technical note examines the potential for preparing template DNA in polymerase chain reactions (PCR) from urine in Japanese macaques (Macaca fuscata). Microsatellite band patterns from urine samples showed close agreement with those of blood and fecal samples, and only a few hundred microl of urine yielded a template DNA for PCR. This research will increase the opportunity for scientists to examine the genetic backgrounds of their target animals by using non-invasive sample collection in the wild.

Simple and effective procedure for complete urine collection from infant macaques (Macaca nemestrina).

A diaper method, used in pediatric medicine, has been adapted and validated for total urine collection from infant macaques (Macaca nemestrina). The device consists of cellulose sponges and polyethylene sheets. The method proposed is non-invasive, simple, and does not significantly hinder the movement of the infant. The method should be useful when one is conducting pharmacokinetic studies in which total urine collection is required.

Characterization of the estrogenic properties of a nonsteroidal estrogen, equol, extracted from urine of pregnant macaques.

Recent reports of substantial urinary levels of equol in pregnant macaques and humans pose a concern, because equol poisoning in the ovine is characterized by an often permanent failure of reproductive processes. Equol (Fig. 1), a metabolite of phytoestrogens, is thought to act through estrogen receptors. The present study made a direct comparison of the estrogenic activity of equol from macaque urine, (+/-) equol and 17 beta-estradiol (E2) in vitro and in vivo. Relative binding affinity of equol for rat uterine receptor was 1% that of E2, and the dissociation rate of equol from the receptor was very high. Consistent with equol's binding properties in vitro, it was ineffective in stimulating rat uterine weight gain and possessed limited ability to increase progesterone receptor. Uterine nuclear receptors after doses of equol sufficient to produce depletion and replenishment of cytosol estrogen receptor were not measurable by exchange assay. No antiestrogenic activity of equol could be demonstrated. Equol's weak potency and lack of antiestrogenic activity are difficult to reconcile with its ability to induce ovine infertility. We conclude species differences at some level other than classical estrogen receptor as defined in the rat model are responsible for variability in equol's impact.

Identification of a non-steroidal estrogen, equol, in the urine of pregnant macaques: correlation with steroidal estrogen excretion.

Macaque urinary estrogens at late pregnancy were separated by high performance liquid chromatography and quantified, both with radioimmunoassay and an in vitro uterine estrogen receptor assay. Five estrogens were measured. Four were steroids: estriol, estrone, 17 beta-estradiol, and 16 alpha-hydroxyestrone. The fifth was a flavonoid, equol, a metabolite of plant isoflavonoids, formononetin and genistein. By mass, estrone and equol were the predominant urinary estrogens, with equol reaching levels of microgram/mg creatinine in three of 8 pregnancies studied. Both quality and quantity of urinary estrogen excretion in the rhesus (Macaca mulatta) was compared to those in 4 other species (Macaca fascicularis, Macaca nemestrina, Macaca radiata and Macaca silenus). All 5 estrogens present in the rhesus were also present in the other 4. Variability in mass of each estrogen excreted appeared no greater between species than within the rhesus. In a longitudinal study, urinary equol levels were most highly correlated with those of estrone, the predominant excretory steroid of macaque pregnancy. We conclude endogenous steroidal estrogen is related to production of equol in macaques, however, equol is not dependent on the feto-placental unit as low levels of equol were also present in male macaque urine.

Metabolism of prostacyclin in Cynomolgus monkey.

The metabolism of prostacyclin (PGI2) in vivo was investigated in Cynomolgus monkey. Following intravenous infusion of 11-[3H]-PGI2 for three days, pooled urine was extracted with Amberlite XAD-2, then chromatographed and purified by Sephadex LH-20, and reverse phase column chromatography. Radioactive fractions were converted to appropriate derivatives for identification by gas chromatography mass spectrometry. Twelve metabolites were characterized, the major of which was 6-keto-PGF1 alpha, accounting for 13% of the urinary radioactivity. The metabolic pathways are similar to those observed earlier in the rat. The excretion of substantial amounts of unchanged 6-keto-PGF1 alpha indicated that the monkey was not able to metabolize PGI2 as avidly as the rat.

Adrenergic and dopaminergic response to chronic chair restraint in the rhesus monkey.

Prolonged chair restraint and social isolation in the rhesus monkey led to a reduction in the urinary excretion of HVA (4-hydroxy-3-methoxyphenylacetic acid), DOPAC (3,4-dihydroxyphenylacetic acid), VMA methoxy-4-hydroxymandelic acid), and MHPG (3-methoxy-4-hydroxyphenylethylglycol) over a 3 week period. This adaptation to a chronically "stressful" situation corresponds to earlier studies on the rhesus monkey indicating a gradual reduction in the urinary excretion of norepinephrine and epinephrine after initiation of restraint. The following basic information on the urinary excretion of catecholamine metabolites was obtained: (1) the rate of excretion of the dopamine metabolites (HVA and DOPAC) is about four times higher than the rate of excretion of adrenergic metabolites (VMA and MHPG): (2) MHPG is the major adrenergic metabolite in the rhesus monkey; and (3) the excretion rates of the urinary metabolites varied considerably between animals.

The pattern of urinary excretion of corticosteroids in Rhesus monkeys (Macaca mulatta).

Urinary total 17-oxogenic steroids (17-OGS), cortisol, cortisone, corticosterone, tetrahydrocortisol (THF), allo-tetrahydrocortisol (all-THF), tetrahydrocortisone (THE), cortols and cortolones, were estimated by established methods in 30 female and 20 male rhesus monkeys. The pattern of the excretion of these steroids in this species was comparable with the human corticosteroids excretion, irrespective of sex difference. The results obtained from this investigation show that they could be used during the study of adrenocortical function and cortisol metabolism in this species.

Urinary metabolites of 2, 5, 2', 5'-tetrachlorobiphenyl in the nonhuman primate.

The metabolism of 2, 5, 2', 5'-tetrachlorobiphenyl (TCB) in nonhuman primates was found to be different from that previously reported in lower species. Monohydroxy TCB (I), the only metabolite in the ether extracts of rat urine, is a minor metabolite in the urine of nonhuman primates. The two major metabolites identified in the urine were dihydroxy TCB (II) and trans-3,4-dihydro-3,4-dihydroxy TCB (III). A second minor metabolite was identified as hydroxy-3,4-dihydro-3,4-dihydroxy TCB (IV). None of the above mentioned metabolites have been reported in primates and only I and III have been identified in lower animals. It is concluded that a likely mechanism for metabolism of TCB in primates is through arene oxide intermediates. This observation is of particular importance in that these types of intermediates are known to alkylate cellular components causing carcinogenic, mutagenic, necrogenic and teratogenic effects.